Over time, Winchester-type fixed disk drives have evolved from large computer peripheral devices having large rotating storage disks and hydraulic head positioning mechanisms into disk drives having very small, fully enclosed packages for inclusion entirely within a housing of small computing systems, such as workstations, personal computers, and portable or laptop computers. Coupled with the miniaturization of disk drives, disk diameters have been reduced from 24 inches to as small as 1.8 inches.
Generally, the external package width and length dimensions of a disk drive define what is known in the art as the "form factor" of the disk drive. While disk drive form factors have progressively decreased, the aerial data storage density of the storage disk has increased dramatically. As such, physically very small disk drives provide the same or greater user data storage capacity than characterized much larger disk drives of only a few years ago.
The reduction of disk drive form factors has permitted direct integration of disk drives into portable or laptop computers. However, a constraint that confronts a developer of such portable computers is the limited amount of power that is available from the power pack, usually a rechargeable battery. Since a disk drive typically consumes a large fraction of the total available power in a portable computer, a disk drive which consumes less power for a given amount of storage capacity is desirable.
Furthermore, environmental concerns about energy conservation have made it desirable to reduce the power consumed by high-capacity disk drives used in desktop computer systems. Since the operation of disk drives significantly contributes to the total power used by a computer, a reduction in disk drive power consumption would in turn reduce the total power used by the computer.
High capacity, contemporary disk drives typically include multiple disks arranged in a commonly journalled stack. A plurality of transducer heads, positioned by a transducer head actuator assembly, are used to access data stored on the surfaces of the disks. Although disk drives containing multiple disks advantageously store significant quantities of data, it has been observed that such disk drives consume more power than disk drives containing a single disk. The higher power consumption is due to increased torque needed to change the momentum of a larger mass of air proximate (between) the multiple disks. The frictional drag between the disk surfaces and the air mass is known as a windage loss. In addition, the power consumption of a disk drive containing multiple disks is particularly increased when the disks are rotated at high speed, e.g. 7200 rpm. Thus, it would be advantageous to confine and control the mass of air proximate the rotating disks in an effort to reduce the power consumption of a disk drive.
One effort to confine and control the air mass proximate the disks in a disk drive having multiple disks is disclosed in U.S. Pat. No. 4,280,155 issued Jul. 21, 1981. Specifically, this patent discloses apparatus for controlling airflow turbulence within a large disk drive, e.g., a disk drive having disks of about eight inches in diameter. The disclosed apparatus is a cover assembly that encloses the entire disk drive assembly. The cover assembly encloses the disk drive assembly in a housing that surrounds about 270.degree. of the disks' circumference. Furthermore, to control airflow turbulence, the disks are spaced from one another by 0.9 inches. In addition, the '155 patent also discloses using vanes, in a fan-like configuration attached to the rotating disk mounting hub of the disk drive and operating in combination with the enclosure, to reduce the temperature within the disk drive by controlling and directing air flow through the drive.
Moreover, the characterization and control of airflow between and near disks in disk drives was investigated and disclosed in E. Lennemann, "Aerodynamic Aspects of Disk Files", IBM J. Res. Develop., November, 1974, pp. 480-488. Therein, airflow phenomena were described as forming particular patterns within the drive depending upon the number of disks and actuator arm position over the disk(s).
Therefore, a need exists in the art for an economical means of reducing the amount of total power consumed during operation of a disk drive, especially, a disk drive containing multiple disks.